1. Field of the Invention
This invention relates to top board structures for keyboard instruments such as grand pianos that are covered with top boards (or lids), wherein a player's fingers will not be caught in top boards when closed.
2. Description of the Related Art
Conventionally, grand pianos having top boards for covering cases are widely used, wherein grand pianos of a folded type are designed such that top boards are each divided into two pieces called top board rears, which are pivotally supported at one ends of cases of grand pianos and can be freely closed and opened, and top board fronts that are arranged in front sides of top board rears and are interconnected using hinges. When top boards are opened, a top board front is folded with hinges to be partially mounted onto a top board rear; then, the free end of the top board rear is lifted up together with the top board front.
Other types of grand pianos are designed not to use hinges for establishing interconnections between top boards and cases so that top board rears are not mutually interconnected with top board fronts, wherein they are independently closed and opened. That is, in a top board structure of an independent type, a top board rear is solely closed or opened while a top board front is closed. Therefore, compared with the top board structure of the folded type, it is possible to reduce weight of the top board rear in operation by the weight of the top board front; that is, it is possible to reduce loads in closing and opening top boards.
An example of a top board structure for a keyboard instrument is disclosed in Japanese Unexamined Patent Publication No. 2001-83960.
In the top board structure of the independent type in which each of the top board rear and top board front can be independently closed and opened, it is possible to prevent dust from entering into the inside of a case of a grand piano when the top board rear and/or top board front is closed. That is, the top board structure of the independent type can be designed to extremely reduce a gap between the top board rear and top board front. In other words, a player (or a user) may be anxious that tips of fingers will be unexpectedly caught in the gap between the top board rear and top board front when the player holds the front end of the top board rear in proximity to the top board front with the fingers. In order to prevent finger tips from being caught in the gap between the top board rear and top board front, the player (or user) should again take hold of the free end of the top board rear by slightly changing positions of fingers. Therefore, the player (or user) may experience difficulties in performing open/close operations of the top board rear, which are very troublesome.